Engine starter gearing



I Nov. 30, 1948. D. L..MILLER Y 2,455,339

' ENGINE STARTER GEAR-[N6 Filed Nov. 27. 1946 ATTbgNEY Patented Nov. 30, 1948 ENGINE STARTER GEARIN G Donald L. Miller, Pine City, N. Y., assignor to Bendix Aviation Corporation, a corporation of Delaware Application November 27, 1946, Serial No. 712,544

8 Claims.

The present invention relates to engine starter gearing and more particularly to automatically engaging drive gearing which is arranged to maintain its engagement with the engine to be started, as lon as the starting system is energized.

It is an object of the present invention to provide a novel starter drive of the character set forth which is efiicient and reliable in operation while being simple and economical in com struction.

It is another object to provide such a device incorporating a yielding transmission member of elastically deformable material which is positively held under a predetermined initial compression.

It is another object to provide such a device incorporating a clutch which is arranged to overrun freely when the engine fires, but which reengages promptly so as to resume cranking if the engine does not continue to be self-operative.

It is another object to provide such a device incorporating anti-drift spring means for normally holding the parts in idle position, which means also functions to increase the transmission of torque from the starting pinion to the control nut when the drive is being demeshed.

It is another object of the invention to provide such a device incorporating elastic means for urgin the members of the overrunning clutch out of engagement so as to overrun freely, said anti-drift spring being arranged to overcome said means and bring the clutch members into frictional engagement to expedite the demeshing of I the pinion from the engine gear.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing, in which:

Fig. 1 is a side elevation partly in section of a preferred embodiment of the invention, the parts being shown in normal or idle position;

Fig. 2 is a similar view showing the parts in cranking position;

Fig, 3 is a similar view showing the parts in the position assumed when the engine fires and overruns the drive while the starting system remains operative; and

Fig. 4 is a detail showing a variant form of the overruning clutch connection to the pinion.

In Fig. 1 of the drawing, there is illustrated a power shaft l which is the extended armature shaft of a starting motor, a portion of which is indicated at 2. A screw shaft 3 is rigidly mounted on the power shaft in any suitable manner as by means clutch member of a cross pin 4 which is retained in the enlarged end 5 of the screw shaft by means of a flanged ring 6 seated against a shoulder 1 on the screw shaft.

2 A pinion 8 is slidably journalled on the power .shaft I for movement into and out of mesh with a gear 9 of the engine to be started, and means .for actuating the pinion from the screw shaft 3 .is provided comprising a control nut ll having a radial flange l2, threaded on the screw shaft 3 .and having a sleeve I3 fixed thereon in any suitable manner as by welding or brazing as indicated at l4. A yielding drivin member in the form of a cylindrical block l5 of elastically deformable material such as rubber is seated at one end on the control nut II and sleeve l3, against the flange l2 of the control nut, and bears frictionally at its other end against a driving overrunning clutch member l6 which is slidably journalled on the free end of the sleeve l3. Clutch member I6 is pressed against the end of the elastic member I 5 so as to hold it under initial compression by means of a radial flange l1 formed on the end of the sleeve I3 by flaring or expanding the end of the sleeve after the elastic member and clutch member have been assembled thereon. I

A driven overrunnin clutch member I8 is rigidly mounted on the pinion 8 as indicated at I9, and the adjacent surfaces of the clutch members l6, l8 are provided with ratchet teeth 2|, 22 respectively which are so inclined as to engage positively when the starting motor drives the pinion for cranking the engine but to cam out and overrun when the engine fires and accelerates the pinion 8 above the speed of the starting motor. A light compression spring 23 is located between peripheral shoulders 24 and 25 on the l6, l8 respectively and urges the clutch members apart while forming a frictional connection therebetween by virtue of the engagement of the end convolutions of the spring with said shoulders 24, 25. A packing sleeve 26 may be seated on the clutch members It, I8 between the shoulders 24, 25 as indicated in order to prevent any lubricant on the screw shaft from escaping between the teeth 2|, 22 of the overrunning clutch members and coming into contact with the elastic member I5.

Means for enclosing the drive and for limiting the meshing movement of the pinion 8 is provided in the form of a barrel member 21 surrounding the control nut ll, elastic block I 5 and overrunning clutch members I6, l8. Barrel 2! has a thrust ring 28 retained in its open end as by on the-flanged ring ment of the barrel brings the -'tions illustrated in-Fig.

35 which loosely surrounds the power shaft l andis arranged to come into abutting relation with the adjacent end of the screw shaft 3-so as to; define the meshed position ofthe pinion 8 as shown in Fig. 2; a thrust washer 36 being preferably interposed between the abutting surfaces to reduce wear.

An anti-drift portion 33 of the barrel, being seated at one end 6 and at-its other end bearing against the thrust washer 3B,'whereby it serves to'urge the barrel, and consequently thepinion 8 and its associated parts, toward idle position as shown in Fig. 1. Spring 31 is considerably stiffer :than the clutch spring 23 whereby when the parts are in idle position, the clutch spring is compressed and the clutch-members I6, l8 'are maintained in engagement asillustrated in Fig. 1.

Means are provided for cooperating :with the latch ring 32, to restrict thedemeshingmovement of the barrel and its associated parts as long as the starting circuit is energized. As here shown, this means is in the form of a plunger 38' which is manually controlled, preferably by being mounted on the end of i the starting switch plunger '40. When the starting switch is closed, the plunger 33 is projected into engagement with the barrel 2'], and when the longitudina'l movelatch ring32 into registry with theplunger, the latter enters a peripheral pocket 39 in the latchring in the manner more fully described and claimed in the application of Oliver, Ser. No. 653;!75, filed March '12, 1946, and assigned-to the assignee of the'present application.

In operation, starting with the parts in the posil, energizationpf the starting system causes the plunger 38 to be projected against the periphery of the barrel "'21, while rotation of the power shaft! in-the direction of the arrow it causes the control nut H to more the longitudinally movable parts'to the right until the pinion 8 is full'y'meshed with the engine gear 9. The longitudinal movement of the barrel is then arrestedby the engagementof the thrust Washer 38 against the end of the screw shaft 3, whereupon further rotation of thepower shaft I and screw shaft 3 causes the control nut H to compress the rubber block '5 against the driving clutch member IB .untilsufficient torque is built up to cause rotation ofthe engine gear 9.

W'hcn the engine fires, the acceleration of the pinion :8 thereby is transmitted backthrough the clutch members and the el-as'tic r-nen'iber l5 to the control nut, whereby it-rnoves back on the screw shaft until the flange l2 engages the shoulder at of the barrehiat which time: the

clutch members 1'6, 18, are disengaged as" shown in Fig; 3. Further backward movement of the barrel is arrested by the plunger 38, so that the anti-drift spring 31 has no effect upon the over,-

running clutch membersi which are accordingly spring 3'1 is located in the reduced body of the spring so that they held apart by the spring 23 so that t ey overrun quietly and freely.

If the engine should not continue to run under its own power, as soon as the pinion 8 slows down below the speed of the screw shaft, the control nut l l is retarded by its frictional connection to the pinion through the clutch spring 23, whereby the control nut and its associated parts are again traversed-into operative position, and cranking is resumed.

3 When the operator is satisfied that t e engine is reliably self-operative, he deenergizes the starting system by opening the starting switch, thereby withdrawing the plunger 38.

- The anti-drift spring 31 is thereupon effective to urge the parts toward idle position, at the same time pressing together the clutch elements l6, l8, whereby the friction transmitted therethrough assists in returning the control nut to its normal position.

a In Fig. 4, there is illustrated an optional variation in the overrunning clutch structure. As there shown, the clutch spring 43 is formed with its end convolutions slightly smaller thanthe grip the clutch members l6, E8, the direction of winding of the spring being such that when the driving clutch member 58 is rotated faster than the driven clutch member 48, the spring will wrap down and grip the clutch members, whereas when the clutch member 18 overruns the clutch member l6, the spring unwraps and releases the clutch members. The packing sleeve 46 is in this case located within the clutch members so as to perform its function without interfering with the action of the clutch spring 43.

The operation of this embodiment is the same as previously described except that the controlling function of the clutch spring 43 is performed more positively in securing reengagement of the clutch members, by virtue of its wrap-down action which increases the frictional connection in the driving direction but reduces the friction during overrun.

Although certain structure has been shown and described in detail, it will be understood that other embodiments are possible and various changes may be made in the design and arrangement of the parts without departing from the spirit of the invention as defined in the claims appended hereto. What is claimed is: H 1. In an engine starter drive, a power shaft, a screw shaft fixed thereon, a pinion slidably journalled on the power shaft for longitudinal movement into .and out of mesh with a gear of an engineto' be started, a control nut threaded on the screw shaft, means for actuating the pinion from the control nut including an elastically deformable member, a driving clutch member in frictional engagement with the elastic member, means for holding the elastic member compressed'between the control nut and driving clutch member, a driven clutch member fixed to connecting the driving and driven clutch members.

3. An engine starter drive as set forth in claim 1, including further, yielding means frictionally connecting the driving and driven clutch members, said yielding means urging the clutch members out of engagement with each other.

4. An engine starter drive as set forth in claim 1, including further, yielding means frictionally connecting the driving and driven clutch members, said yielding means urging the clutch members out of engagement with each other, said anti-drift means being eifective to overcome said yielding means and press the clutch members together upon release of the arresting means for the barrel.

5. In an engine starter drive, a power shaft, a pinion slidably journalled thereon for movement into and out of mesh with a gear of an engine to be started, means responsive to acceleration of the power shaft for moving the pinion into mesh with the engine gear and thereafter rotating the pinion from the power shaft, said means including an overrunning clutch, releasable means for holding the pinion in mesh with the engine gear, and anti-drift means including a spring efiective on release of the holding means for moving the pinion out of mesh and retaining it in idle position, said anti-drift means including means for pressing together the members of the overrunning clutch to cause the transmission of torque therethrough from the pinion.

6. An engine starter drive as set forth in claim 5, in which the means for rotating the pinion is effective to clamp together the members of the overrunning clutch incidental to the transmission of torque therethrough.

7. An engine starter drive as set forth in claim 5, including further, resilient means urging the 6 members of the overrunning clutch apart while providing a frictional connection therebetween, said anti-drift means being effective to overcome the resilient means and cause frictional engagement of the overrunning clutch members when the holding means is released.

8. In an engine starter drive, a power shaft, a screw shaft fixed thereon, a pinion slidably journalled on the power shaft, a flanged control nut threaded on the screw shaft, a sleeve fixed to the control nut, a transmission member of elastically deformable material seated at one end on the sleeve, a driving clutch member slidably journalled on the sleeve, said sleeve having means for holding said clutch member and transmission member under compression, a driven clutch member fixed to the pinion, a barrel surrounding the transmission and clutch members having an abutment at one end for engaging the screw shaft, and a stop at the other end limiting longitudinal movement of the driven clutch member; a spring urging the clutch members apart while providing a frictional connection therebetween, an anti-drift spring effective to compress the clutch spring and urge the barrel toward idle position, and a manually controlled latch means for limiting the demeshing movement of the barrel.

DONALD L. MILLER. REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,420,283 Buxton et al May 6, 1947 2,428,750 Buxton Oct. 7, 1947 

